What Is Double Data Type in SQL?

The double data type in SQL is used to store numbers with decimal places. It is a numeric data type that can hold a larger range of values compared to the float data type. The double data type is also known as “double precision” and is commonly used in scientific and financial calculations.

Double Data Type Syntax

The syntax for declaring a column with the double data type in SQL is as follows:

column_name DOUBLE(p, s)

Here, column_name refers to the name of the column, p represents the precision (total number of digits), and s represents the scale (number of decimal places).

Example:

CREATE TABLE employees (
   employee_id INT,
   salary DOUBLE(10, 2)
);

In this example, we create a table named “employees” with two columns: “employee_id” of INT data type and “salary” of DOUBLE data type with a precision of 10 and scale of 2.

Double Data Type Range

The range of values that can be stored in a double data type depends on the precision specified. The maximum precision for a double data type varies across different database systems. However, it typically allows for at least 15 digits.

Example:

• A double data type with a precision of 5 and scale of 2 can store values like: -999.99 to 999.99.
• A double data type with a precision of 10 and scale of 3 can store values like: -99999.999 to 99999.999.

It’s important to note that the actual range of values may depend on the specific database system being used.

Double vs. Float

In SQL, both double and float data types are used to store numbers with decimal places. However, there are some differences between the two:

• Precision: Double data type offers a higher precision compared to float data type. It can store a larger number of significant digits.
• Storage: The double data type typically requires more storage space compared to float data type.
• Performance: Float calculations may be faster than double calculations due to their lower precision.

The choice between using double or float depends on the specific requirements of your application and the level of precision needed for your calculations.

Conclusion

The double data type in SQL is a numeric data type used to store numbers with decimal places. It offers a higher precision compared to the float data type and is commonly used in scientific and financial calculations. Understanding the range, syntax, and differences between double and float can help you make informed decisions when designing your database schema.